Method for Automatically Regulating the Size of a Slot of a Nozzle Assembly and Control and/or Regulation System

ABSTRACT

The invention relates to a method for automatically regulating the size of a nozzle discharge slot of a nozzle assembly, wherein the nozzle assembly comprises a first and a second nozzle lip and a nozzle discharge slot arranged between the nozzle lips for setting in a controlled manner a thickness profile of a conveyable melt. A plurality of adjusting elements, in particular a plurality of adjusting pins, coupled to a respective thermoelement, is arranged on the first nozzle lip, the thermoelements being controllable by the regulation in such a way that the slot can be adjusted by the action of a mechanical force from the respective adjusting element on the first nozzle lip, as a result of the expansion or contraction of the thermoelements. At least two adjusting elements are adjusted simultaneously. The invention further relates to a control and/or regulation system.

The present invention relates to a method for automatically regulatingthe size of a nozzle discharge slot of a nozzle assembly. The inventionfurther relates to a control and/or regulation system.

In flat film applications, such as the production of films or bands ofthermoplastic plastics, automatic nozzles are used in the prior art toform an extruded plastic melt into a thin rectangular surface or film.The automatic nozzles comprise a first and a second nozzle lip as wellas a nozzle discharge slot arranged between the nozzle lips for settingin a controlled manner a thickness profile of the conveyable melt. Onthe first nozzle lip a plurality of adjusting elements is arranged,which are each coupled to a thermoelement. When heated, thethermoelements expand and exert mechanical pressure on the nozzle lipvia the associated adjusting element, causing the nozzle lip to deformat the corresponding location. In particular, this reduces the nozzledischarge slot. Furthermore, the thermoelements can compress duringcooling and cause a mechanical pull on the nozzle lip via the adjustingelements, which increases the nozzle discharge slot at the correspondinglocation. The thermoelements can be controlled by a nozzle regulation insuch a way that the slot can be adjusted by the action of a mechanicalforce applied to the first nozzle lip by the respective adjustingelement as a result of the expansion or contraction of thethermoelements.

It is important that the controlled thickness profile of the melt can beachieved by setting or adjusting the nozzle discharge slot. Thethickness profile is especially important for subsequent processes suchas winding of film webs for storage or further processing of the filminto bags. For monitoring the thickness profile, thickness gauges, inparticular by means of ultrasonic or infrared measurements, are known tobe used in such a way that cross profile deviations in a net region ofthe film or melt are continuously minimized in order to avoid so-calledpiston rings on the film roll. In other words, deviations from a nominalprofile of the film are continuously determined by means of a thicknessmeasurement, and a control value for the individual thermoelements oradjusting elements at the nozzle lip is then generated, so that thenozzle discharge slot is locally increased or reduced for a uniformthickness. As a measurable and indicated quality criterion of a flatfilm produced by means of a nozzle regulation, a statistical 2- or3-sigma deviation of the measured film thickness from an average valueor a nominal value is usually specified.

A prerequisite for the function of nozzle regulations is a precise,manual setting of a homogeneous nozzle discharge slot adapted to theproduct to be produced. Consequently, before the initial operation and,if necessary, during the nozzle regulation, an additional setting ofindividual adjusting elements of the nozzle assembly must be carried outby the operator in such a way that a stable process is achieved.

The process of setting the nozzle discharge slot is often carried outmanually during a production interruption by manually closing or openingindividual adjusting elements by the operator. This adjustment ofindividual adjusting elements can be very time-consuming.

Due to the mutual, in particular asymmetrical influence of the adjustingelements in relation to the bending curve of the nozzle lip (transverseinfluence), a disadvantageous profile tolerance with a 2-sigma deviationof the thickness profile of more than 20-40% can occur even after manualcentering of the nozzle discharge slot. The manual centering of thenozzle discharge slot is largely dependent on the professionalexperience of the operator. Furthermore, manual centering istime-consuming and sometimes not completely reproducible and theindividual adjusting elements have to be set or adjusted repeatedly oneafter the other during production with every further initial operationor with every further deviation from the nominal value of the thicknessprofile.

The targeted manipulation of individual or several adjusting elements bythe operator is a—complex method and based on the experience andknowledge. In production practice, this knowledge is not available toall machine operators, so that often only reactive reactions toseemingly and obvious process disturbances, such as a deteriorating rollquality, are possible. A reaction to less obvious problems with thenozzle regulation—such as reaching the maximum possible adjustment rangeof individual adjusting elements—is rather rare. In addition, it can beobserved in operational practice that the setting up of the nozzleassembly by the operator with regard to the basic control value and themanual setting of the adjusting elements in the edge region oftenrepresents a compromise of the products normally run on the machine. Aproduct-dependent optimization is usually not carried out for reasons oftime and/or competence. Instead, lower line speeds are often accepteddue to process instabilities, in particular in the edge region.

It is therefore an object of the present invention to at least partiallyeliminate the disadvantages described above. In particular, it is anobject of the present invention to provide a setting of the nozzledischarge slot with an improved precision and/or a reduced expenditureof time.

The previous object is solved by a method with the features of claim 1.Furthermore, the object is solved by a control and/or regulation systemwith the features of claim 10. Further features and details of theinvention result from the dependent claims, the description and thefigures. Features and details which are described in relation to themethod according to the invention are of course also valid in relationto the control and/or regulation system according to the invention andvice versa, so that with regard to the disclosure of the individualaspects of the invention reference is or can always be made to eachother.

In the context of the application, the term of the regulation preferablycomprises control and/or regulation methods and/or machine learningmethods, to which a measured variable can be fed as an input signal intothe regulation with regard to the thickness profile and/or thecharacteristic properties of the melt and, based on this, a setting oradjustment of individual or all adjusting elements or thermoelements canbe carried out. The adjustment is carried out by means of a controlvalue or control signal generated by the regulation for the individualadjusting elements or the respective thermoelements.

Furthermore, in the context of the application, the term “pinning”comprises in particular the adhesion or fixing of the melt to a castingroll. Adhesion can preferably be effected electrostatically orpneumatically.

In the context of the application, adjusting elements are defined aselements for local adjustment of the nozzle discharge slot, such asthermal expansion pins, step/servo motors or piezo actuators.Furthermore, piezomechanical adjusting elements or adjusting elementsoperated by electrochemical volume changes are generally conceivable.

According to a first aspect of the invention, the object is solved by amethod for automatically regulating the size of a nozzle discharge slotof a nozzle assembly, wherein the nozzle assembly comprises a first anda second nozzle lip and a nozzle discharge slot arranged between thenozzle lips for setting in a controlled manner a thickness profile of aconveyable melt. A plurality of adjusting elements, in particular aplurality of adjusting pins, which are coupled to a respectivethermoelement, is arranged at the first nozzle lip, wherein thethermoelements are controllable by the regulation in such a way that theslot adjustment can be realized by the action of a mechanical force fromthe respective adjusting element on the first nozzle lip as a result ofan expansion or contraction of the thermoelements. At least twoadjusting elements are adjusted simultaneously.

The invention has the advantage that the simultaneous, in particularautomatic, adjustment of at least two adjusting elements can eliminatethe need for a time-consuming manual adjustment of individual adjustingelements one after the other by saving a large number of iterations bythe operator. Thus, the entire production process can be significantlyaccelerated. In the same way, the simultaneous adjustment of twoadjusting elements, in particular of two adjacent adjusting elements,can reduce the transverse influence of the adjusting elements.

Preferably, it may be provided that all adjusting elements are adjustedsimultaneously. This has the advantage that the production process canbe further accelerated. The simultaneous adjustment of all adjustingelements also allows a targeted influence on the edge region. Thisallows the entire width of the nozzle discharge slot, including theright-hand and left-hand edge regions, to be regulated and optimallyset.

In a preferred embodiment, it may be provided that the adjustingelements are adjusted over an equal stroke, thus enabling paralleladjustment. In particular, all adjusting elements can preferably beadjusted symmetrically, wherein a standardized nozzle discharge slot ofthe nozzle assembly can be set. Due to the standardized nozzle dischargeslot, a high reproducibility is given, which enables the continuousproduct quality at each further initial operation. The setting of thestandardized nozzle discharge slot can be exemplarily made depending onthe melt or the material of the product to be produced. The setting oradjustment of the adjusting elements can be done by means of astandardized setting of the torque of the adjusting elements, whereinthe adjusting elements comprise an equal or essentially equal contactpressure against the first nozzle lip.

Within the scope of the invention, it is further conceivable that theadjusting elements are adjusted depending on the type of melt and/ordepending on the size of a basic slot of the nozzle assembly. Inparticular, the material of the melt, the operating temperature or melttemperature or the recipe of the melt, in particular its viscosityand/or viscoelasticity, can be taken into account. This has theadvantage that a setting of the nozzle discharge slot can be determinedvery precisely for the specific material. Furthermore, the setting canpreferably be made with regard to quality and/or stability criteria ofthe melt and/or the production process, such as the line speed and/orthe length of the melt plume.

Further preferably it is conceivable that the adjustment of theadjusting elements occurs automatically based on measurement signals ofat least one sensor, wherein the sensor is designed and/or arranged atthe nozzle assembly in such a way that conclusions can be drawn aboutthe thickness profile, in particular the edge region, of the melt. Bycomparing the measured thickness profile with a nominal value, a basiccontrol value for the individual adjusting elements can be generated bythe regulation so that a deviation from the nominal value is a maximumof 30%, in particular a maximum of 10%, preferably in the range of 2% to5%. The regulation also comprises a data processing unit, which isconfigured in such a way that the measurement signals of the sensor areprocessed and, based on this, a control signal or control value isgenerated for the adjusting elements or the respective thermoelementsfor adjusting the slot of the nozzle discharge slot. In other words, theprocessing of the measurement signals of the sensor results in thecontrol or regulation of single, several or all adjusting elements ofthe nozzle assembly. As a result, a melt flow distribution optimized forprocess stability and product quality and the resulting shaping of theedge of the melt plume and/or film is achieved.

In a further embodiment it is provided that the at least one sensor isdesigned as a temperature sensor or optical sensor and/or measures theflow behavior of the melt, in particular at the edge. The at least onesensor is preferably connected to the regulation by data communicationfor the transmission of measurement signals. For example, the sensor canbe designed as a temperature sensor, an infrared or ultrasonic sensor oras an optical sensor. As an example, the sensor can be designed as acamera for optical image acquisition of the melt. The sensor canpreferably be arranged at a casting roll to measure the temperature ofthe melt emerging from the nozzle discharge slot and conveyed at thecasting roll. In particular, several sensors can be provided for theprecision of the measurement of the thickness profile and/or differentlydesigned sensors can be combined.

Preferably, it may be provided that, at an initial operation of thenozzle assembly for conveying the melt, the adjusting elements forsubsequent regulation of the slot size are set uniquely free from playas the initial setting. This has the advantage that the setting of theadjusting elements free from play allows an exact alignment of thenozzle discharge slot. If there is too much play in the adjustingelements, the heating or cooling of the thermoelements can sometimes notlead to a deformation of the nozzle lip, but the change in length of thethermoelements is partially lost without effect in the play of thenozzle assembly. Furthermore, the setting of the adjusting elements freefrom play at the initial operation of the nozzle assembly allows areproducible starting point for the nozzle regulation. This generallyincreases the process stability, for example to advantageously increasethe line speed when conveying the melt through the nozzle assembly, orto significantly increase the efficiency of a flat film facility. Thereproducible, setting free from play also allows for increased qualityconsistency for different products, resulting in improved results forboth new machine and retrofit business. In particular, the setting freefrom play at the initial operation of the nozzle assembly can be carriedout automatically, thus avoiding any manual intervention by an operator.Thus, a high reproducibility in the basic setting of the nozzle assemblyand/or during production can be ensured. This also generally simplifiesthe machine setup and significantly shortens the setup time of thenozzle assembly before production. It also reduces the need for furthermanual settings by the operator during production to regulate thethickness profile.

It is also preferably conceivable that an adjustment of the adjustingelements is carried out automatically based on measurement signals of atleast one sensor, wherein the sensor is designed and/or arranged at thenozzle assembly in such a way that conclusions can be drawn about thethickness profile of the melt and the right-hand and left-hand edgeregion of the melt is monitored by means of the sensor and is controlledor regulated in such a way that the respective edge region is set byadjusting the adjusting elements depending on the material, inparticular viscosity and/or viscoelasticity, and/or quality criteriaand/or a conveying speed. This has the advantage that the edge region ofthe melt or film which is outside the net region is explicitlyconsidered and evaluated. By monitoring the edge region of the melt, theentire thickness profile can be optimally set. Therefore, the entirewidth of the nozzle discharge slot can be used advantageously. The edgeregion can be evaluated with regard to quality and/or stabilitycriteria, in particular depending on the product to be produced and/orthe production process. Furthermore, it is advantageous that bymonitoring the edge region and the corresponding adjustment of theadjusting elements, the edge region can be set in such a way that anedge trim can be reduced. The material of the melt can therefore beoptimally utilized.

Furthermore, the design of the melt flow distribution at the nozzledischarge slot, in particular in the edge region (and consequently thestability resulting there) can be exemplarily designed depending on anoperating point (e.g. an output or a temperature of the melt) and arecipe (e.g. viscosity or viscoelasticity). For example, in the case ofhigh output and/or high melt viscosity, the nozzle discharge slot can bebent up further in a central region. This in turn can result in areduced melt flow in the edge regions. The nozzle regulation canadvantageously compensate for this and carry out appropriate settings ofadjusting elements so that the film edge meets the defined stabilitycriteria. Furthermore, in the case of a very thin film, it can beadvantageous to create a stable, thicker edge region to ensure processstability even at high line speeds. With a thick film, on the otherhand, it is advantageous to set the film edge to be correspondinglythinner due to its slower cooling. By means of the nozzle regulation andthe setting of the edge regions, the design of the film edges istherefore known, reproducible and, in particular, symmetrical.Correspondingly, the regulation enables high process stability andproduct quality.

Furthermore, it can be advantageously provided that at least oneclamping blade is respectively arranged in a right-hand and left-handedge region of the nozzle assembly, wherein the width of the nozzledischarge slot can be variably set, wherein the method for adjusting thewidth of the nozzle discharge slot and for clamping the adjustingelements can be carried out automatically and comprises the followingsteps:

-   -   unclamping the clamping blade within the nozzle discharge slot;    -   displacing the clamping blade within the nozzle discharge slot;    -   clamping the clamping blade within the nozzle discharge slot for        fixing individual adjusting elements.

This has the advantage that the automatic setting of the clamping bladesfor a width adjustment of the nozzle discharge slot results insignificant time savings in the production process, as no manualadjustment by the operator is required. In addition, the nozzleregulation provides the basis for another customer benefit, namely fullyautomatic width adjustment in a flat film facility. Therefore, a veryflexible format of the flat film can be realized. The process ofautomating the adjustment of the clamping blades can achieve largersales volumes and relieve the operator of the nozzle assembly inphysical and psychological terms. Furthermore, the precision of theadjustment of the clamping blades can be increased by the automation.

Preferably, a standardized nozzle discharge slot of the nozzle assemblyis set by means of the setting of the adjusting elements free from play.For this purpose, the adjusting elements can be adjusted symmetrically.The standardized nozzle discharge slot ensures a high degree ofreproducibility, which enables continuous product quality at eachsubsequent initial operation. The setting of the standardized nozzledischarge slot can be exemplarily carried out depending on the melt orthe material of the product to be produced. Furthermore, thestandardized setting allows the reduced set-up time of the nozzleassembly for the production.

In a preferred embodiment, it may be provided that the degree of freedomfrom play of the adjusting elements is set depending on the type of meltand/or depending on the size of a basic slot of the nozzle assembly. Inparticular, the material of the melt, the operating temperature or melttemperature or the recipe of the melt, in particular its viscosityand/or viscoelasticity, can be taken into account. Furthermore, thedegree of freedom from play can be set preferably with regard to qualityand/or stability criteria of the melt and/or the production process,such as the line speed and/or the length of the melt plume.

Within the scope of the invention it is further conceivable that thesetting of the adjusting elements free from play is achieved by means ofa standardized setting of the torque of the adjusting element, whereinthe adjusting elements comprise an equal or substantially equal contactpressure against the first nozzle lip. In particular, the standardizedsetting of the torque of the adjusting elements can be carried out with2 Nm. This has the advantage that no manual setting of a mechanicalnozzle discharge slot adapted to the product to be produced is necessaryfor the regulation. The adjusting elements of the nozzle assembly areonly set uniquely at the initial operation or re-operation of the nozzleassembly in such a way that all adjusting elements cause an essentiallyequal low pressure on the nozzle lip. In other words, the adjustingelements cause an equal slight deformation of the nozzle lip or a slightincrease or decrease of the nozzle discharge slot.

In a preferred embodiment it is provided that the adjusting elements areset as an initial setting to a maximum opening stroke of the nozzleassembly. This has the advantage that a specific centering of the nozzledischarge slot can be omitted if the maximum opening stroke of thenozzle assembly is used as a starting point for the regulation. Thisenables time savings in the production. Furthermore, it is not necessaryto set individual adjusting elements by the operator to achieve theuniform film thickness distribution required for the initial operationof the nozzle regulation to a 2-sigma tolerance of, for example, 10%.The inventive nozzle regulation can also achieve a regulated toleranceof approx. 10% during production, starting from an unregulated toleranceof more than 20% at the initial operation, in particular more than 30%or in particular more than 40%. In particular, it is advantageouslypossible to enable a reproducible operation and production of the nozzleassembly, since with the help of the nozzle regulation, the adjustmentor setting of all adjusting elements is known at any time.

Preferably, it may be provided that the setting of the adjustingelements free from play is stored and/or integrated as a self-learningalgorithm for a renewed initial operation of the nozzle assembly. Thishas the advantage that a specific initial operation with pre-storedsettings is possible for a renewed film production, which furtherincreases the reproducibility of the setting of the nozzle dischargeslot. In particular, the setting free from play can be stored as arecipe value and/or automatically regulated with respect to specificpredefined criteria and/or implemented as a self-learning algorithm.

In a further preferred embodiment of the invention, it is conceivablethat subsequent to the initial setting, the adjusting elements areautomatically regulated along the entire width of the nozzle assemblyfor the slot adjustment, in particular in an edge region of the nozzleassembly. After the unique setting of the nozzle assembly according tothe above described embodiments, the setting of the nozzle dischargeslot suitable for the product is carried out by means of the automaticnozzle regulation. It is advantageous that the regulation is carried outalong the entire width of the nozzle discharge slot. Since the adjustingelements are thus also set in the right-hand and left-hand edge regionof the nozzle discharge slot, it is not necessary for the operator toiteratively create a stable film edge during production by manuallyadjusting them. The regulation can comprise a targeted influence on themelt flow distribution during the initial operation and in theproduction, in particular in the edge region of the nozzle assembly, sothat a stable edge of the melt is achieved here without userintervention. In other words, the thickness profile is also regulatedoutside the net region of the film.

It is preferable that individual adjusting elements are adjusted with atime delay. This has the advantage that a product-specific andcharacteristic formation of the melt plume can be achieved.

In a preferred embodiment, it is provided that, in particular when aregulation limit is reached, a simultaneous adjustment of individual orseveral adjusting elements occurs. The regulation limit can represent amaximum or minimum opening of the nozzle discharge slot. It is thereforeadvantageous to react as quickly as possible to an excessive opening orclosing of the nozzle discharge slot by adjusting the adjustingelements.

It is preferably conceivable that by means of electrostatics and/or airan edge adhesion of the melt emerging from the nozzle assembly to acasting roll occurs, wherein the edge adhesion, in particular thestrength of the edge adhesion and/or the position on the casting roll,is set by means of the regulation depending on the material and/orquality criteria and/or the conveying speed. The edge adhesion describesan adhesion of the melt emerging from the nozzle discharge slot to thecasting roll, for example via electrostatics (“electrostatic pinning”)and/or via air (“air pinning”) In particular, electrostatic pinningbetween an edge thickening and the net region of the film can lead to athin section, as the electrostatic attracts melt particles from bothsides. The characteristics of the thin section depends, for example, onthe melt flow distribution at the nozzle discharge slot, on theviscoelastic behavior of the melt and on process settings such as theline speed, the length of the melt plume, the strength of the pinning aswell as other feeding devices such as a vacuum box or an air knife. Aparticular advantage of the nozzle regulation is the reproducible designof the film edge, which in contrast to the prior art, allows a mucheasier and also reproducible setting of the pinning. The nozzleregulation can also comprise setting hints or specifications for thepositioning and strength of the pinning.

A further advantage is that the edge adhesion is continuously monitoredand/or detected during the operation of the nozzle assembly. This hasthe advantage that the result of the setting of the pinning isreproducibly detected and can be optimized according to intended qualitycriteria.

Alternatively or additionally, it may be provided that the edge adhesionis detected by means of a multidimensional motorized traversing and/oran optical system and/or a temperature detection of the melt on thecasting roll and/or sensors to determine the thickness profile of themelt. The detection of the pinning position or the position of the edgeadhesion can be done by means of a 1-, 2- or 3-dimensional (motorized)traversing or by optical systems. The detection of the pinning result(e.g. the shape of the edge region) can be done by temperature detectionof the melt on the casting roll and/or by conventional thicknessmeasurement systems, which measure the entire film width and provide asprecise information as possible about the shape of the edge.Furthermore, the pinning result can be detected by means of a traversingsensor, in particular an infrared sensor or an FPM sensor, below a pointof impact on the casting roll and/or by means of conventional thicknessmeasurement systems. Suitable quality criteria for the stability of theedge are, for example, the position of the thin section, the ratio ofthin to thick sections, the form and/or shape of the thin and thicksections, the detected temperature profile in the edge region and thedetected profile of the film thickness in the edge region. In additionto the control values for regulating the adjusting elements, the nozzleregulation can also generate the necessary information for settingand/or controlling and/or regulating electrostatic and pneumaticpinning. This contributes significantly to the already describedincrease in process stability.

Within the scope of the invention it is further conceivable that thespecific setting of the adjusting elements depending on the material, inparticular the viscosity and/or viscoelasticity, and/or quality criteriaand/or the conveying speed is stored and/or integrated as aself-learning algorithm for a renewed initial operation of the nozzleassembly. This has the advantage that a targeted initial operation withpre-stored settings is possible for a renewed film production, whichfurther increases the reproducibility of the setting of the nozzledischarge slot. In particular, the setting free from play can be storedas a recipe value and/or automatically regulated with respect tospecific predefined criteria and/or implemented as a self-learningalgorithm.

Preferably, it may be intended that the unclamping and/or clamping ofthe clamping blade occurs thermally. In particular, the unclampingand/or clamping of the clamping blade can be carried out by means of acorresponding thermoelement, which is coupled with the clamping blade.The thermoelements expand when heated and thereby exert a mechanicalpressure on the corresponding clamping blade. As an example, thethermoelements can be controlled by the regulation in such a way thatthe clamping blade is unclamped and/or clamped by an expansion orcontraction of the thermoelements. By means of the thermal unclampingand/or clamping a well controllable fine adjustment can be realized.This enables an exact positioning and/or contact pressure alignment ofthe clamping blades and therefore guarantees a qualitatively improvedand at the same time automated setting of the clamping blades.

In a preferred embodiment it may be provided that when the clampingblade is displaced to reduce the nozzle discharge slot, a specific, inparticular pre-stored, setting of the adjusting elements, in particularin an edge region, is transferred to the reduced nozzle discharge slotaccordingly. This has the advantage that a targeted initial operationwith pre-stored settings is enabled during a renewed film production,which further increases the reproducibility of the setting of the nozzledischarge slot. In particular, the setting of the adjusting elements canbe stored as a recipe value and/or automatically regulated with respectto specific predefined criteria. By transferring the setting of theadjusting elements during a format adjustment of the width of the nozzledischarge slot, an optimal adaptation to the new width can be achieved.In addition, the transfer of the settings scaled to the width of thenozzle discharge slot results in further time savings in the production.

Within the scope of the invention, it is further conceivable that priorto displacing the clamping blade, an examination of the necessity ofadjusting the specific, in particular pre-stored, setting of theadjusting elements, in particular in an edge region, is carried out. Theexamination can occur in particular depending on the melt or thematerial of the product to be produced. In particular, the material ofthe melt, the operating temperature or melt temperature or the recipe ofthe melt, in particular its viscosity and/or viscoelasticity, can betaken into account. Furthermore, the examination can preferably be setwith regard to quality and/or stability criteria of the melt and/or theprocess, such as the line speed and/or the length of the melt plume.Advantageously, specific edge settings can be transferred to the newedge section inwards and an automatic format adjustment of the nozzledischarge slot can be performed.

Alternatively or additionally, it is conceivable that, when the clampingblade is displaced to reduce the nozzle discharge slot, a specific, inparticular pre-stored, setting of an edge adhesion of the melt emergingfrom the nozzle assembly on a casting roll is transferred to the reducednozzle discharge slot accordingly by means of electrostatics and/or air.By transferring the setting for the edge adhesion in the case of aformat adjustment of the width of the nozzle discharge slot, an optimaladaptation to the new width can be further improved.

Preferably, it may be provided that, when the clamping blade isdisplaced and clamped to reduce the nozzle discharge slot, the fixedadjusting elements are excluded from the regulation. In a preferredembodiment, it may be provided that the fixed adjusting elements are setto an exact nominal value by the regulation. This has the advantage thatthe nominal value can be set to a defined value for the adjustingelements fixed by the clamping blade, in particular a maximum or minimumopening stroke, so that the fixed adjusting elements do not change theirposition. This ensures a tightness of the nozzle assembly, since thefixed adjusting elements preferably do not allow melt to pass throughthe nozzle discharge slot. This ensures that no melt escapes outside theintended edge region of the nozzle discharge slot.

In a preferred embodiment, it may be provided that the regulation of theadjusting elements for setting the nozzle discharge width is based onstored and/or historical profiles. This has the advantage that, in caseof a new film production, a targeted initial operation and productionwith pre-stored settings is possible, which further increases thereproducibility of the setting of the nozzle discharge slot. It is alsoadvantageous to derive quantitative and/or qualitative learning stepsfrom the history for the setting of the nozzle discharge width.

Advantageously, it is conceivable that the displacement of the clampingblade is limited to a maximum adjustment torque. This provides, forexample, protection against damage and/or an incorrect setting of theclamping blade. The limitation of the displacement of the clamping bladecan be selected depending on the material, in particular viscosityand/or viscoelasticity, and/or quality criteria and/or the conveyingspeed for the nozzle assembly. Thus, an optimal setting for theproduction process can occur.

Alternatively or additionally, it is conceivable that the displacementof the clamping blade is motorized. Therefore, no manual intervention ofthe operator is required. Furthermore, the motorized displacement of theclamping blade is in particular useful for the full automation of thenozzle assembly.

According to a further aspect of the invention, a control and/orregulation system with a control unit is provided for carrying out themethod according to one of the preceding embodiments. Features anddetails described in connection with the method according to theinvention are of course also valid in connection with the control and/orregulation system according to the invention and vice versa, so thatwith respect to the disclosure of the individual aspects of theinvention, reference is or can always be made to each other.

The invention is explained in more detail below on the basis ofnon-restrictive embodiment examples, which are shown in the figures. Thefigures show:

FIG. 1 a schematic view of an inventive nozzle assembly according to afirst embodiment;

FIG. 2 a schematic view of an inventive nozzle assembly according to afurther embodiment with a characteristic thickness profile;

FIG. 3 each a schematic diagram of a regulation according to theinvention with a simultaneous and parallel adjustment of the adjustingelements;

FIG. 4 each a schematic diagram of a regulation according to theinvention for the transfer of the setting of the adjusting elements inan edge region.

In the following figures, similar elements are marked with the samereference signs for reasons of clarity.

FIG. 1 shows a schematic view of a nozzle assembly 10 according to theinvention for an automated regulation of the size of a nozzle dischargeslot according to a first exemplary embodiment. The nozzle assembly 10comprises a first nozzle lip 12 and a second nozzle lip 14. A nozzledischarge slot 16 is arranged between the nozzle lips 12, 14 for thecontrolled setting of a thickness profile of a conveyable melt. Themelt, for example a plastic melt for the production of a flat film, isconveyed through the nozzle discharge slot 16. Depending on the size orheight of the nozzle discharge slot 16, the thickness of the melt is setor changed.

To set the size or height of the nozzle discharge slot 16, a pluralityof adjusting elements 20, in particular approx. 120 adjusting elements20, is arranged on the first nozzle lip 12. Only one adjusting element20 is shown symbolically in FIG. 1.

The adjusting element 20 is exemplarily designed as an adjusting pin,which comprises a tapering shape in the direction of the first nozzlelip 12. The tapered shape tapers to a point-shaped tip. The point-shapedtip forms a minimum contact surface between the adjusting element 20 andthe first nozzle lip 12. In other words, the adjusting element 20 isconnected to the first nozzle lip 12 via the point-shaped tip.

The adjusting element 20 is coupled with a respective thermoelement 30.When heated, the thermoelement 30 expands and exerts a mechanicalpressure on the first nozzle lip 12 via the respective adjusting element20, causing it to deform at the corresponding location. In particular,the nozzle discharge slot 16 is thus reduced. Furthermore, thethermoelement 30 can compress during cooling and causes a mechanicalpull on the first nozzle lip 12 via the adjusting element 20, whichincreases the nozzle discharge slot 16 at the corresponding location.For this purpose, the thermoelement 30 can be controlled by a nozzleregulation in such a way that that the slot can be adjusted by theaction of a mechanical force from the adjusting element 20 on the firstnozzle lip 12, as a result of the expansion or contraction of thethermoelement 30. In other words, the thermoelement 30 can exertpressure on the first nozzle lip 12 by means of an exemplary expansionvia the adjusting element 20. The design of the adjusting element 20with its tapered shape leads in particular to a very precise adjustmentof the nozzle discharge slot 16, since the effect on adjacent adjustingelements is reduced. The nozzle discharge slot 16 is therefore deformedin a limited spatial region of the first nozzle lip 12. Thethermoelement 30 can, for example, be connected to a heating or coolingdevice, which is controlled by the regulation for heating or cooling thethermoelement 30.

For example, at least two adjusting elements 20 can be adjustedsimultaneously. This has the advantage that the simultaneous, inparticular automatic, adjustment of at least two adjusting elements 20eliminates the need for a time-consuming manual adjustment of individualadjusting elements one after the other. Likewise, the simultaneousadjustment of two adjusting elements 20, in particular of two adjacentadjusting elements 20, can reduce the transverse influence of theadjusting elements 20.

At the initial operation of the nozzle assembly 10 for conveying themelt, the adjusting elements 20 can be uniquely set free from play for asubsequent regulation of the slot size of the nozzle discharge slot 16as the initial setting. This has the advantage that an exact alignmentof the nozzle discharge slot 16 is possible. If there is too much playin the adjusting elements 20, the heating or cooling of thethermoelements 30 cannot partially lead to a deformation of the nozzlelip 12. In addition, the setting of the adjusting elements 20 free fromplay allows a reproducible starting point of the nozzle regulation atthe initial operation of the nozzle assembly 10. This generallyincreases the process stability. In particular, the setting free fromplay can be carried out automatically at the initial operation of thenozzle assembly 10, thus avoiding any manual intervention by anoperator.

Furthermore, an adjustment of the adjusting elements 20 can be carriedout automatically based on measurement signals of a non-displayedsensor, wherein the sensor is designed and/or arranged at the nozzleassembly 10 in such a way that conclusions can be drawn about thethickness profile of the melt and the right-hand and left-hand edgeregion of the melt is monitored by means of the sensor and is controlledor regulated in such a way that the respective edge region is set byadjusting the adjusting elements 20 depending on the material, inparticular viscosity and/or viscoelasticity, and/or quality criteriaand/or a conveying speed. This has the advantage that the edge region ofthe melt or film which is outside the net region is explicitlyconsidered and evaluated. By monitoring the edge region of the melt, theentire thickness profile can be optimally set. The edge region can beevaluated with regard to quality and/or stability criteria, inparticular depending on the product to be produced and/or the productionprocess.

Furthermore, at least one clamping blade, not shown, can be arranged ina respective right-hand and left-hand edge region of the nozzle assembly10, wherein the width of the nozzle discharge slot 16 can be variablyset, wherein a method for adjusting the width of the nozzle dischargeslot 16 and for clamping the adjusting elements 20 can be carried outautomatically and comprises the following steps:

-   -   unclamping the clamping blade within the nozzle discharge slot        16;    -   displacing the clamping blade within the nozzle discharge slot        16;    -   clamping the clamping blade within the nozzle discharge slot 16        for fixing individual adjusting elements 20.

This has the advantage that the automatic setting of the clamping bladesfor a width adjustment of the nozzle discharge slot 16 results insignificant time savings in the production process, as no manualadjustment by the operator is required.

FIG. 2 shows a schematic view of a nozzle assembly according to theinvention for the automated regulation of the size of a nozzle dischargeslot according to a further exemplary embodiment with a characteristicthickness profile. The nozzle assembly 10 comprises a non-shown firstnozzle lip 12 and a non-shown second nozzle lip 14. A nozzle dischargeslot 16 is arranged between the nozzle lips 12, 14 for the controlledsetting of a thickness profile of a conveyable melt 50. The melt 50, forexample a plastic melt for the production of a flat film, is conveyedthrough the nozzle discharge slot 16. Depending on the size or height ofthe nozzle discharge slot 16, the thickness of the melt 50 is set orchanged.

For setting the size or height of the nozzle discharge slot 16, aplurality of adjusting elements 20, in particular approx. 120 adjustingelements 20, is arranged on the first nozzle lip 12. Each adjustingelement 20 is coupled with a respective thermoelement 30. When heated,the thermoelement 30 expands and exerts a mechanical pressure on thefirst nozzle lip 12 via the respective adjusting element 20, causing itto deform at the corresponding location. In particular, the nozzledischarge slot 16 is reduced. Furthermore, the thermoelement 30 cancompress during cooling and causes a mechanical pull on the first nozzlelip 12 via the adjusting element 20, which increases the nozzledischarge slot 16 at the corresponding location. For this purpose, thethermoelement 30 can be controlled by a nozzle regulation in such a waythat the slot can be adjusted by the action of a mechanical force fromthe adjusting element 20 on the first nozzle lip 12, as a result of theexpansion or contraction of the thermoelement 30.

The outgoing melt 50 conveyed through the nozzle discharge slot 16 isadhered to a casting roll 40 by means of electrostatics in an exemplarymanner and can then be wound into a sleeve in a subsequent windingdevice. Due to the adhesion the melt 50 can be fixed to the casting roll40. The edge of the melt 50 is characterized by the so-called edge entry(“neck-in”), which is caused by the withdrawal of the melt 50 from thenozzle assembly 10 and the visco-elastic behavior of the melt 50. As aresult of the neck-in, a reduction of the film width at the casting roll40 in relation to the width of the nozzle discharge slot 16, as well asa thickening 70 of the edge region of the film corresponding to thisreduction, occurs. The reduction of the film width is represented by thecurved dotted lines at the melt 50. The thickening 70 is furtherexemplarily illustrated by the characteristic thickness profile of themelt 50.

The y-axis shows the thickness of the melt 50 and the X-axis shows thenozzle width. The thickness of the melt 50 is regulated in such a waythat a constant thickness can be optimally achieved along the entirenozzle width. The characterizing thickening 70 of the right-hand andleft-hand edge region of the nozzle assembly 10 is caused by the neck-inof the melt 50. Due to the electrostatic edge adhesion to the castingroll 40, a thin section 72 can occur between the thickening 70 and aconstant thickness of the melt 50, since the electrostatics attract meltparticles from both sides. The characteristics of the thin section 72depends, for example, on the melt flow distribution at the nozzledischarge slot 16, on the viscoelastic behavior of the melt 50 and onprocess settings such as the line speed, the length of the melt plume,or the strength of the edge adhesion.

The thickness profile of the melt 50 is monitored by a sensor, not shownhere, as an example. The sensor can be designed as an optical sensorand/or arranged on the casting roll 40, so that conclusions can be drawnabout the thickness profile of the melt 50. For this purpose, the sensoris preferably connected to the regulation via data communication for thetransmission of measurement signals.

By comparing the measured thickness profile with a nominal value, abasic control value can be generated by the regulation for theindividual adjusting elements 20 so that a deviation from the nominalvalue is a maximum of 30%, in particular a maximum of 10%, preferably inthe range of 2% to 5%. In other words, the regulation can be used to setan essentially constant thickness of the melt 50. For this purpose, theregulation comprises a data processing unit, which is configured in sucha way that the measurement signals of the sensor are processed and,based on this, a control signal is generated for the adjusting elements20 or the respective thermoelements 30 for adjusting the slot of thenozzle discharge slot 16. In other words, the processing of themeasurement signals of the sensor results in the automatic control orregulation of individual, several or all adjusting elements 20 of thenozzle assembly.

For example, at least two adjusting elements 20 can be adjustedsimultaneously. This has the advantage that the simultaneous, inparticular automatic, adjustment of at least two adjusting elements 20eliminates the need for a time-consuming manual adjustment of individualadjusting elements one after the other. Likewise, the simultaneousadjustment of two adjusting elements 20, in particular of two adjacentadjusting elements 20, can reduce the transverse influence of theadjusting elements 20.

At the initial operation of the nozzle assembly 10 for conveying themelt 50, the adjusting elements 20 can be set uniquely free from playfor a subsequent regulation of the slot size of the nozzle dischargeslot 16 as the initial setting. This has the advantage that an exactalignment of the nozzle discharge slot 16 is possible. In particular,the setting free from play can be carried out automatically at theinitial operation of the nozzle assembly 10, thus avoiding any manualintervention by an operator.

Furthermore, the right-hand and left-hand edge region of the melt 50 canbe monitored by means of the sensor and controlled or regulated in sucha way that the respective edge region is set by adjusting the adjustingelements 20 depending on the material, in particular viscosity and/orviscoelasticity, and/or quality criteria and/or a conveying speed. Thishas the advantage that the edge region of the melt 50, which is outsidethe net region, is explicitly considered and evaluated. By monitoringthe edge region of the melt 50, the entire thickness profile can beoptimally set. The edge region can be evaluated with regard to qualityand/or stability criteria, in particular depending on the product to beproduced and/or the production process.

Furthermore, at least one clamping blade 60 is arranged in a respectiveright-hand and left-hand edge region of the nozzle assembly 10, whereinthe width of the nozzle discharge slot 16 can be variably set, wherein amethod for adjusting the width of the nozzle discharge slot 16 and forclamping the adjusting elements 20 can be carried out automatically andcomprises the following steps:

-   -   unclamping the clamping blade 60 within the nozzle discharge        slot 16;    -   displacing the clamping blade 60 within the nozzle discharge        slot 16;    -   clamping the clamping blade 60 within the nozzle discharge slot        16 for fixing individual adjusting elements 20.

This has the advantage that the automatic setting of the clamping blades60 for a width adjustment of the nozzle discharge slot 16 results insignificant time savings in the production process, as no manualadjustment by the operator is required. Clamping and/or unclamping ofthe clamping blades 60 is done thermally in an exemplary manner. Thedisplacement of the respective clamping blade 60 can be motorized andlimited to a maximum adjustment torque.

FIG. 3 shows a schematic diagram of an inventive regulation of the sizeof a nozzle discharge slot of a nozzle assembly with a simultaneous andparallel adjustment of the adjusting elements. The description of thenozzle assembly 10 is analogous to FIG. 2.

In both diagrams, the y-axis shows the control value for the individualadjusting elements 20 and the x-axis shows the nozzle width. Theindividual adjusting elements 20 are represented by a horizontal line.Thus, there are several adjusting elements 20 at a defined distance fromeach other along the nozzle width. The direction of the arrows shows theadjustment of the adjusting elements 20. An upward adjustment implies acontraction of the thermoelement 30 associated with the adjustingelement 20, which causes a mechanical pull via the adjusting element 20and increases the nozzle discharge slot 16 at the correspondinglocation. A downward adjustment implies an expansion of thethermoelement 30 associated with the adjusting element 20, which causesa mechanical pressure via the adjusting element 20 and reduces thenozzle discharge slot 16 at the corresponding location. The length ofthe individual arrows of the adjusting elements 20 describes the size ofthe control value or the amount of the strength of the adjustment.

In the diagram above, the regulation effects a simultaneous adjustmentof all adjusting elements 20. All adjusting elements 20 are adjustedalong the entire nozzle width, in particular also in the right-hand andleft-hand edge region. The size of the adjustment is based on themeasured thickness profile of the melt 50. To compensate the thicknessprofile in case of deviations from a constant thickness, in particularin the net region of the melt 50, the adjusting elements 20 are adjustedupwards and downwards.

In the diagram below, the regulation effects a simultaneous and paralleladjustment of all adjusting elements 20. All adjusting elements 20 areadjusted symmetrically along the entire nozzle width, in particular alsoin the right-hand and left-hand edge regions. The adjusting elements 20are adjusted over an equal stroke to increase the nozzle discharge slot16. In general, the adjustment of the adjusting elements can occurdepending on the type of melt and/or depending on the size of a basicslot of the nozzle assembly 10.

FIG. 4 shows in each case a schematic diagram of an inventive regulationof the size of a nozzle discharge slot of a nozzle assembly for thetransmission of the setting of the adjusting elements in an edge region.The description of the nozzle assembly 10 is analogous to FIG. 2.

In both diagrams, the y-axis shows the control value for the individualadjusting elements 20 and the x-axis shows the nozzle width. Theindividual adjusting elements 20 are represented by a horizontal line.Thus, there are several adjusting elements 20 at a defined distance fromeach other along the nozzle width.

The diagram above shows an example of a specific setting of theadjusting elements 20 for the entire nozzle width. This specific settingcan occur depending on the material of the melt, in particular itsviscosity and/or viscoelasticity, and/or quality criteria and/or theconveying speed.

In the diagram below, the specific setting of the adjusting elements 20in the respective edge region is transferred as an example from theupper diagram to a reduced nozzle discharge slot or a reduced nozzlewidth. The reduction of the nozzle width is shown by means of the arrowsand realized by means of the clamping blades 60. Before displacing theclamping blades 60, an examination can occur to determine whether thespecific setting needs to be adapted.

The above explanation of the embodiment describes the present inventionexclusively in the context of examples. Of course, individual featuresof the embodiment can be freely combined with each other, if technicallyreasonable, without leaving the scope of the present invention.

LIST OF REFERENCE SIGNS

10 nozzle assembly12 first nozzle lip14 second nozzle lip16 nozzle discharge slot20 adjusting element30 thermoelement40 casting roll50 melt60 clamping blade80 thickening72 thin section

1-10. (canceled)
 11. A method for automatically regulating the size of anozzle discharge slot of a nozzle assembly, wherein the nozzle assemblycomprises a first and a second nozzle lip and a nozzle discharge slotarranged between the nozzle lips for setting in a controlled manner athickness profile of a conveyable melt, wherein a plurality of adjustingelements is arranged at the first nozzle lip, which are coupled to arespective thermoelement, wherein the thermoelements are controllable bythe regulation in such a way that the slot adjustment can be realized bythe action of a mechanical force from the respective adjusting elementon the first nozzle lip as a result of an expansion or contraction ofthe thermoelements, wherein at least two adjusting elements are adjustedsimultaneously.
 12. The method according to claim 11, wherein alladjusting elements are adjusted simultaneously.
 13. The method accordingto claim 11, wherein the adjusting elements are adjusted over an equalstroke, thus enabling parallel adjustment.
 14. The method according toclaim 11, wherein the adjusting elements are adjusted at least dependingon the type of melt or depending on the size of a basic slot of thenozzle assembly.
 15. The method according to claim 11, wherein theadjustment of the adjusting elements occurs automatically based onmeasurement signals of at least one sensor, wherein the sensor is atleast designed or arranged at the nozzle assembly in such a way thatconclusions can be drawn about the thickness profile of the melt. 16.The method according to claim 15, wherein the at least one sensor is atleast designed as a temperature sensor or optical sensor or measures theflow behavior of the melt.
 17. The method according to claim 11, whereinat an initial operation of the nozzle assembly for conveying the melt,the adjusting elements for subsequent regulation of the slot size areset uniquely free from play as the initial setting.
 18. The methodaccording to claim 11, wherein an adjustment of the adjusting elementsis carried out automatically based on measurement signals of at leastone sensor, wherein the sensor is at least designed or arranged at thenozzle assembly in such a way that conclusions can be drawn about thethickness profile of the melt and the right-hand and left-hand edgeregion of the melt is monitored by means of the sensor and is controlledor regulated in such a way that the respective edge region is set byadjusting the adjusting elements depending on at least the material orquality criteria or a conveying speed.
 19. The method according to claim11, wherein at least one clamping blade is respectively arranged in aright-hand and left-hand edge region of the nozzle assembly, wherein thewidth of the nozzle discharge slot can be variably set, wherein themethod comprises the following steps, which are carried outautomatically for adjusting the width of the nozzle discharge slot andfor clamping the adjusting elements: unclamping the clamping bladewithin the nozzle discharge slot; displacing the clamping blade withinthe nozzle discharge slot; clamping the clamping blade within the nozzledischarge slot for fixing individual adjusting elements.
 20. At least acontrol or regulation system with a control unit for carrying out themethod according to claim 11.